CN117558978B - Electrolyte, secondary battery and electric equipment - Google Patents

Electrolyte, secondary battery and electric equipment Download PDF

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Publication number
CN117558978B
CN117558978B CN202410036008.7A CN202410036008A CN117558978B CN 117558978 B CN117558978 B CN 117558978B CN 202410036008 A CN202410036008 A CN 202410036008A CN 117558978 B CN117558978 B CN 117558978B
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electrolyte
radical
injection
primary
battery
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CN117558978A (en
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叶璐
邓柏依
张超
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Sany Hongxiang Battery Co ltd
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Sany Hongxiang Battery Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/60—Arrangements or processes for filling or topping-up with liquids; Arrangements or processes for draining liquids from casings
    • H01M50/609—Arrangements or processes for filling with liquid, e.g. electrolytes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Secondary Cells (AREA)

Abstract

The invention belongs to the technical field of secondary batteries, and particularly relates to electrolyte, a secondary battery and electric equipment. The electrolyte comprises a primary electrolyte injection electrolyte and a secondary electrolyte injection electrolyte, wherein the primary electrolyte injection electrolyte can form a stable SEI film on the surface of the negative electrode, the secondary electrolyte injection electrolyte contains a cationic additive, the uncoated surface of the positive electrode material can be coated in situ, particularly, positive electrode particles are crushed in the circulation process to expose a new uncoated interface, and the cationic additive reacts on the positive electrode surface to form an in-situ coating layer. The in-situ coating layer can avoid the oxidation reaction of the new interface of the anode and the electrolyte in direct contact, thereby remarkably improving the problem of gas production of the battery in a circulating way. In addition, the cationic additive is added during secondary injection, and stable SEI is formed on the surface of the negative electrode, so that the cationic additive cannot deposit on the surface of the negative electrode, the problems of overlarge self-discharge or internal short circuit cannot be caused, and the cycle capacity retention rate is remarkably improved.

Description

Electrolyte, secondary battery and electric equipment
Technical Field
The invention belongs to the technical field of secondary batteries, and particularly relates to electrolyte, a secondary battery and electric equipment.
Background
With the vigorous development of energy storage and new energy automobiles, higher demands are put forward on novel battery systems in terms of service life, energy density, safety, cost and the like. Among the three commonly used alkali metal batteries (lithium ion battery, sodium ion battery, potassium ion battery), lithium ion battery has the highest energy density, and sodium ion battery has the lowest cost, so these two types of batteries have been widely paid attention to and studied. At present, the alkali metal battery is circulated under the conditions of higher voltage and temperature, so that the problem of mass gas production is solved, and the cycle life and the safety are seriously influenced.
There are two current methods for solving the problem of alkali metal gas production: one is to coat or dope the positive electrode material, improve the stability of the positive electrode interface or structure, and further inhibit the rate of oxidation reaction between the positive electrode and the electrolyte; the other is that the electrolyte is optimized, mainly CEI film forming additive is added in the electrolyte, and a protective film is formed on the surface of the positive electrode, so that direct contact with the electrolyte is reduced, and the purpose of reducing gas production is achieved.
The existing alkali metal anode materials mainly comprise two types, namely a monocrystalline anode material and a polycrystalline anode material, wherein stress is generated due to nonuniform expansion of a C axis of the material in the polycrystalline circulation process, so that primary particles are separated from a secondary sphere, and a new interface is formed. Because the new interface is not provided with a coating layer, the new interface is easy to generate oxidation reaction with electrolyte to generate gas. The monocrystalline anode can also have similar conditions, resulting in direct breakage of monocrystalline particles, which form new uncoated interfaces, which react with the electrolyte to produce a large amount of gas. Therefore, the existing solution is coated in the material preparation process, the problem of gas production in the circulation process cannot be solved, and the CEI film-forming additive also has the problems of unobvious gas production improvement effect in the circulation process, rapid reduction of the circulation capacity retention rate, overlarge self-discharge or internal short circuit and the like.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the defects of the electrolyte in the prior art in the application process, so as to provide the electrolyte, the secondary battery and the electric equipment.
Therefore, the invention provides the following technical scheme:
The invention provides an electrolyte, which comprises a primary injection electrolyte and a secondary injection electrolyte, wherein the primary injection electrolyte comprises alkali metal salt, a nonaqueous solvent and a primary additive;
The secondary injection electrolyte comprises a cationic additive and a nonaqueous solvent, wherein cations in the cationic additive comprise at least one of Al 3+、Zr4+、Ti3+、Ta4+、Mg2+.
When the cation additive contains two or more cations, the cations may be mixed in any ratio.
Optionally, the cation additive comprises at least one of nitrate, sulfate, sulfite, chloride, acetate, oxalate, hexafluoroarsenate, tetrafluoroborate, perchlorate, hexafluoroantimonate, difluorophosphate, 4, 5-dicyano-2-trifluoromethylimidazole, bis-oxalate borate, bis-malonate borate, difluoro-oxalate borate, bis-difluoromalonate borate, malonate oxalate borate, difluoro-oxalate borate, tri-oxalate phosphate, trifluoro-malonate phosphate, tetrafluorooxalate phosphate, difluoro-dioxalate phosphate, difluoro-sulfonimide, bis-trifluoromethanesulfonyl imide, fluoro-sulfon-trifluoro-methanesulfonimide, fluoride ion; when a plurality of anions are contained at the same time, the anions may be mixed in any ratio.
Optionally, the cationic additive accounts for 0.1% -30% by weight of the total mass of the secondary injection electrolyte;
optionally, the cationic additive accounts for 5% -8% of the total mass of the secondary injection electrolyte.
Optionally, the primary injection electrolyte accounts for 30% -99.9% by weight of the total mass of the electrolyte; the secondary injection electrolyte accounts for 0.1% -70%.
Optionally, the primary injection electrolyte accounts for 60% -80% by weight of the total mass of the electrolyte; the secondary injection electrolyte accounts for 20% -40%.
Optionally, the alkali metal salt accounts for 12% -20% of the total mass of the electrolyte for one injection, and the primary additive accounts for 1% -5%.
Alternatively, the alkali metal salt is a lithium salt, a sodium salt or a potassium salt.
In the present invention, the primary additive is a conventional additive in the art. Typically, without limitation, the primary additive includes at least one of ethylene carbonate, 1, 3-propane sultone, trifluoromethyl ethylene carbonate, dimethyl sulfate, ethylene sulfate, vinyl methyl sulfate, propylene sulfate, ethylene sulfite, succinic anhydride, biphenyl, diphenyl ether, toluene, xylene, cyclohexylbenzene, fluorobenzene, p-fluorotoluene, p-fluoroanisole, t-butylbenzene, t-pentylbenzene, propenolactone, butane sultone, methylene methane disulfonate, ethylene glycol dipropylene nitrile ether, hexamethyldisilazane, heptamethyldisilazane, dimethyl methylphosphonate, diethyl ethylphosphonate, trimethyl phosphate, triethyl phosphate, triphenyl phosphite, tris (trimethylsilyl) borate, tris (trimethylsilyl) phosphate; when the plurality of primary additives are selected, the plurality of primary additives may be mixed in an arbitrary ratio. Preferably, the primary additive is vinylene carbonate.
In the invention, the nonaqueous solvent in the primary injection electrolyte and the secondary injection electrolyte is a solvent conventional in the field. Typically, and without limitation, the nonaqueous solvent in the primary and secondary liquid electrolytes independently comprises at least one of sulfolane, dimethyl sulfoxide, methylene chloride, ethylene dichloride, ethylene carbonate, butylene carbonate, difluoroethylene carbonate, dimethyl fluorocarbonate, methyl fluorocarbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl carbonate, methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate, methyl difluoroacetate, ethyl difluoroacetate, gamma-butyrolactone, gamma-valerolactone, delta-valerolactone, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, fluoroether, tetrahydrofuran, 2-methyltetrahydrofuran, 1, 3-dioxane, 1, 4-dioxane; when a plurality of nonaqueous solvents are selected, the nonaqueous solvents can be mixed in any proportion; preferably, the nonaqueous solvent is a mixture of Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC), and the mass ratio of the ethylene carbonate to the ethylmethyl carbonate to the diethyl carbonate is 2:5:3.
In the present invention, the lithium salt is a lithium salt which is conventional in the art. Typically, without limitation, the lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluoroantimonate, lithium difluorophosphate, lithium 4, 5-dicyano-2-trifluoromethylimidazole, lithium bisoxalato borate, lithium bismalonate borate, lithium difluorooxalato borate, lithium malonate oxalato borate, lithium tris (difluoromalonate) phosphate, lithium tetrafluorooxalato phosphate, lithium difluorodioxaato phosphate, lithium difluorosulfonimide, lithium fluorosulfonyl triflimide, lithium nitrate, lithium fluoride; when a plurality of lithium salts are selected, the plurality of lithium salts may be mixed in an arbitrary ratio; preferably, the lithium salt is a mixture of lithium hexafluorophosphate and lithium bis (fluorosulfonyl) imide, and the mass ratio of the two can be 17:2.
In the present invention, the sodium salt is a sodium salt which is conventional in the art. Typically, without limitation, the sodium salt includes at least one of sodium hexafluorophosphate, sodium tetrafluoroborate, sodium perchlorate, sodium hexafluoroarsenate, sodium hexafluoroantimonate, sodium difluorophosphate, sodium 4, 5-dicyano-2-trifluoromethylimidazole, sodium bisoxalato borate, sodium bismalonate borate, sodium difluorooxalato borate, sodium malonate oxalato borate, sodium trioxalato phosphate, sodium tris (difluoromalonate) phosphate, sodium tetrafluorooxalato phosphate, sodium difluorodioxalato phosphate, sodium difluorosulfonimide, sodium fluorosulfonyl triflimide, sodium nitrate, sodium fluoride; when a plurality of sodium salts are selected, the plurality of sodium salts can be mixed in any proportion; preferably, the sodium salt is a mixture of sodium hexafluorophosphate and sodium bis-fluorosulfonyl imide, and the mass ratio of the sodium salt to the sodium bis-fluorosulfonyl imide can be 15:1.
In the present invention, the potassium salt is a potassium salt which is conventional in the art. Typically, without limitation, the potassium salt includes at least one of potassium hexafluorophosphate, potassium tetrafluoroborate, potassium perchlorate, potassium hexafluoroarsenate, potassium hexafluoroantimonate, potassium difluorophosphate, potassium 4, 5-dicyano-2-trifluoromethylimidazole, potassium bisoxalato borate, potassium bismalonate borate, potassium difluorooxalato borate, potassium malonate oxalato borate, potassium trifluorooxalate phosphate, potassium tris (difluoromalonate) phosphate, potassium tetrafluorooxalate phosphate, potassium difluorodioxalate phosphate, potassium difluorosulfonimide, potassium fluorosulfonyl trifluoromethanesulfonimide, potassium nitrate, potassium fluoride; when the plurality of potassium salts are selected, the plurality of potassium salts may be mixed in any ratio.
The invention also provides a secondary battery comprising the electrolyte.
The invention also provides electric equipment, which comprises the secondary battery.
In the invention, the electrolyte injection method is a conventional method in the field. Typically, but not by way of limitation, the electrolyte is provided by the following method: performing primary injection on the battery cell without the injection, and injecting primary injection electrolyte;
Packaging, standing, hot-cold pressing, and forming according to a common chemical forming process (the invention is not particularly limited), and pre-circulating for 1 time at 45 ℃.
Then injecting electrolyte into the battery core for the second time;
finally, the working procedures of aging, capacity division, K value test or packaging and the like of the battery cells are finished according to the common process in the industry (the invention is not particularly limited), and the required battery is obtained.
In the present invention, the composition and the preparation method of the secondary battery are all conventional methods in the field. Typically, without limitation, the composition and method of making the lithium ion battery may include:
(1) Preparing a positive plate of a lithium ion battery:
96 parts of lithium ion battery positive electrode active material, 2 parts of binder PVDF and 2 parts of conductive carbon black are dispersed in N-methyl pyrrolidone to obtain uniform positive electrode active material slurry, and then the slurry is uniformly coated on two surfaces of an aluminum foil current collector, and the positive electrode sheet is obtained through drying and roller press compaction.
(2) Preparing a negative electrode sheet:
95 parts of negative electrode material, 2 parts of styrene-butadiene rubber, 1.5 parts of sodium carboxymethylcellulose and 1.5 parts of conductive carbon black are mixed and dispersed in deionized water to obtain uniformly dispersed negative electrode active material slurry. And coating the prepared slurry on one side of a copper foil, drying the pole piece, and compacting by a roller press to obtain the negative pole piece.
(3) And (3) assembling a battery cell:
Sequentially stacking the prepared positive pole piece, the diaphragm and the negative pole piece, so that the diaphragm is positioned between the positive pole piece and the negative pole piece, and stacking to obtain a bare cell; and placing the bare cell in an aluminum plastic film outer package.
(4) Preparation of electrolyte:
in a glove box filled with argon, the moisture content was < 0.1ppm and the oxygen content was < 0.1ppm. And (3) preparing a primary injection electrolyte: mixing the nonaqueous solvent to obtain an organic solvent, slowly adding lithium salt into the organic solvent to obtain a mixture of the organic solvent and the lithium salt, finally adding a primary additive, and uniformly stirring to obtain the primary injection electrolyte of the lithium ion battery. And (3) preparing a secondary injection electrolyte: and mixing the nonaqueous solvent to obtain an organic solvent, slowly adding the cationic additive into the organic solvent, and uniformly stirring to obtain the secondary electrolyte injection electrolyte of the lithium ion battery.
(5) Liquid injection and pre-circulation
First liquid injection: and (3) vacuum drying the battery core at 85 ℃, injecting the prepared primary injection electrolyte into the dried battery core after the water reaches the standard, and packaging, standing, hot-cold pressing and forming according to a common method in industry.
Pre-cycling: and placing the battery cell in a 45 ℃ incubator, and standing for 30 minutes to keep the lithium ion battery at a constant temperature. The lithium ion battery having reached the constant temperature is charged to the upper limit voltage (lithium battery upper limit voltage 4.5V) with a constant current of 1C, then charged to a constant voltage (the upper limit voltage of the aforementioned constant current charging) until the current drops to 0.05C, and then discharged to the lower limit voltage (lithium battery lower limit voltage 2.8V) with a constant current of 1C.
And (3) liquid injection for the second time: and injecting the prepared secondary injection electrolyte, packaging, performing laser welding and sealing on the battery aluminum shell and the cover plate, performing procedures such as battery cell aging, capacity division, K value test and packaging, and the like, and completing the preparation of the lithium ion battery.
The composition and preparation method of the sodium ion battery can comprise the following steps:
(1) Preparing a positive plate of the sodium ion battery:
Dispersing 96 parts of sodium ion battery anode material, 2 parts of binder PVDF and 2 parts of conductive carbon black in N-methyl pyrrolidone to obtain uniform anode active material slurry, uniformly coating the slurry on two surfaces of an aluminum foil current collector, drying at 80-120 ℃ for 30-60 minutes, and compacting by a roller press to obtain an anode sheet PN.
(2) Preparing a negative electrode sheet:
95 parts of negative electrode material, 2 parts of styrene-butadiene rubber, 1.5 parts of sodium carboxymethylcellulose and 1.5 parts of conductive carbon black are mixed and dispersed in deionized water to obtain uniformly dispersed negative electrode active material slurry. And coating the prepared slurry on one side of a copper foil, drying the pole piece, and compacting by a roller press to obtain a negative pole piece NN.
(3) And (3) assembling a battery cell:
sequentially stacking the prepared positive pole piece PN, the diaphragm and the negative pole piece NN, so that the diaphragm is positioned between the positive pole piece and the negative pole piece, and stacking to obtain a bare cell; and placing the bare cell in an aluminum plastic film outer package.
(4) Preparation of electrolyte:
In a glove box filled with argon, the moisture content was < 0.1ppm and the oxygen content was < 0.1ppm. And (3) preparing a primary injection electrolyte: mixing the nonaqueous solvent to obtain an organic solvent, slowly adding sodium salt into the organic solvent to obtain a mixture of the organic solvent and the sodium salt, adding the primary additive, and uniformly stirring to obtain the primary injection electrolyte of the sodium ion battery. And (3) preparing a secondary injection electrolyte: mixing the nonaqueous solvent to obtain an organic solvent, slowly adding the cationic additive into the organic solvent, and uniformly stirring to obtain the secondary electrolyte injection of the sodium ion battery.
(5) Liquid injection and pre-circulation
First liquid injection: the battery cell is dried in vacuum at 85 ℃, and after the water reaches the standard, the prepared primary injection electrolyte is injected into the dried battery cell, and packaging, standing, hot-cold pressing and formation are carried out according to a common method in industry (the specific operation is not limited by the invention).
Pre-cycling: and placing the battery cell in a 45 ℃ incubator, and standing for 30 minutes to keep the lithium ion battery at a constant temperature. The lithium ion battery having reached the constant temperature was charged to the upper limit voltage (sodium battery upper limit voltage 4.0V) with a constant current of 1C, then charged to a constant voltage (the upper limit voltage of the aforementioned constant current charging) until the current decreased to 0.05C, and then discharged to the lower limit voltage (sodium battery lower limit voltage 1.5V) with a constant current of 1C.
And (3) liquid injection for the second time: and injecting the prepared secondary injection electrolyte, packaging, performing laser welding and sealing on the battery aluminum shell and the cover plate, aging the battery core, separating the capacity, testing the K value or packaging and the like, and thus completing the preparation of the sodium ion battery.
The electric device provided in the present invention employing the above secondary battery is not particularly limited. Typically, but not limited to, the powered device includes, but is not limited to, a cell phone, a notebook computer, a tablet computer, a pen-input computer, a portable facsimile machine, a portable copier, a portable printer, a transceiver, a video recorder, a camera, a television, a radio, a portable audio recorder, a portable CD player, a mini-compact disc, an electronic book player, an electronic organizer, a wearable device (e.g., a smart watch, a smart bracelet, a headset, a bluetooth headset), a portable cleaner, a calculator, a memory card, a backup power source, an automobile, a motorcycle, a bicycle (e.g., a power assisted bicycle), a lighting fixture (e.g., a flash), a toy, a game machine, a clock, an electric tool, a household large battery, a capacitor, and the like.
The technical scheme of the invention has the following advantages:
The electrolyte provided by the invention comprises a primary injection electrolyte and a secondary injection electrolyte, wherein the primary injection electrolyte comprises alkali metal salt, a nonaqueous solvent and a primary additive; the secondary injection electrolyte comprises a cationic additive and a nonaqueous solvent, wherein cations in the cationic additive comprise at least one of Al 3+、Zr4+、Ti3+、Ta4+、Mg2+. The primary injection electrolyte can form a stable SEI film on the surface of the negative electrode, the secondary injection electrolyte contains a cationic additive, the uncoated surface of the positive electrode material can be coated in situ, particularly, positive electrode particles are crushed in the circulation process to expose a new uncoated interface, and the cationic additive reacts on the surface of the positive electrode to form an in-situ coating layer. The in-situ coating layer can avoid the oxidation reaction of the new interface of the anode and the electrolyte in direct contact, thereby remarkably improving the problem of gas production of the battery in a circulating way. In addition, the cationic additive is added during secondary injection, and stable SEI is formed on the surface of the negative electrode, so that the cationic additive cannot be deposited on the surface of the negative electrode, the problem of overlarge self-discharge or internal short circuit cannot be caused (gas production and circulation are improved, and meanwhile, self-discharge amplification and internal short circuit cannot be caused), and the circulation capacity retention rate is remarkably improved.
Detailed Description
The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments described herein, but are not intended to limit the scope of the invention, any product which is the same or similar to the present invention, whether in light of the present teachings or in combination with other prior art features, falls within the scope of the present invention.
The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge.
1 Part=10g in the following examples and comparative examples.
Example 1
The embodiment provides an electrolyte and a sodium ion battery, and the specific composition and preparation method are as follows:
(1) Preparing a positive plate of the sodium ion battery:
96 parts of sodium ion battery anode layered oxide NaNi 0.4Fe0.2Cu0.1Mn0.3, 2 parts of binder PVDF and 2 parts of conductive carbon black are dispersed in N-methyl pyrrolidone to obtain uniform anode active material slurry, then the slurry is uniformly coated on two sides of an aluminum foil current collector, drying is carried out for 50 minutes at 100 ℃, and a roller press is used for compaction, so that an anode pole piece PN with the double-sided density of 330g/m 2 is obtained.
(2) Preparing a negative electrode sheet:
95 parts of hard carbon, 2 parts of styrene-butadiene rubber, 1.5 parts of sodium carboxymethylcellulose and 1.5 parts of conductive carbon black are mixed and dispersed in deionized water to obtain uniformly dispersed anode active material slurry. And coating the prepared slurry on one side of a copper foil, drying the pole piece, and compacting by a roller press to obtain the negative pole piece NN with the surface density of 160g/m 2.
(3) And (3) assembling a battery cell:
sequentially stacking the prepared positive electrode PN, diaphragm (composition: polyethylene substrate 9 micron+2 micron ceramic coating) and negative electrode NN, so that the diaphragm is positioned between the positive electrode and the negative electrode, and stacking to obtain a bare cell; and placing the bare cell in an aluminum plastic film outer package.
(4) Preparation of electrolyte:
In a glove box filled with argon, the moisture content was < 0.1ppm and the oxygen content was < 0.1ppm. And (3) preparing a primary injection electrolyte: mixing Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) according to a mass ratio of 2:5:3 to obtain an organic solvent, slowly adding 15wt% of sodium hexafluorophosphate (NaPF 6) and 1wt% of sodium difluorosulfimide (NaFSI) based on the total weight of the primary injection electrolyte into the organic solvent to obtain a mixture of the organic solvent and sodium salt, finally adding 3wt% of ethylene carbonate (VC) based on the total weight of the electrolyte, and uniformly stirring to obtain the primary injection electrolyte of the sodium ion battery. And (3) preparing a secondary injection electrolyte: mixing Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) according to a mass ratio of 2:5:3 to obtain an organic solvent, slowly adding titanium acetate (Ti (CH 3COO)3) accounting for 7wt% of the total weight of the secondary injection electrolyte into the organic solvent, and uniformly stirring to obtain the secondary injection electrolyte of the sodium ion battery.
(5) Liquid injection and pre-circulation
First liquid injection: the battery cell is dried in vacuum at 85 ℃, 105 g of the prepared primary injection electrolyte is injected into the dried battery cell after the water reaches the standard, and the battery cell is packaged, kept stand, hot-cold pressed and formed according to the common method in industry.
Pre-cycling: and placing the battery cell in a 45 ℃ incubator, and standing for 30 minutes to keep the sodium ion battery at a constant temperature. The sodium ion battery reaching the constant temperature is charged to 4.0V at a constant current of 1C, then charged at a constant voltage until the current drops to 0.05C, and then discharged to 1.5V at a constant current of 1C.
And (3) liquid injection for the second time: and injecting 45 g of the prepared secondary injection electrolyte, packaging, performing laser welding and sealing on the battery aluminum shell and the cover plate, aging the battery core, separating the capacity, testing the K value, packaging and the like, and thus completing the preparation of the sodium ion battery.
Examples 2 to 13 and comparative examples 1 to 3
Examples 2 to 13 and comparative examples 1 to 3 were prepared according to the sodium ion battery preparation method of example 1 described above, and specific substances and contents are shown in table 1 below.
TABLE 1
Example 14
The embodiment provides an electrolyte and a lithium ion battery, and the specific composition and preparation method are as follows:
(1) Preparing a positive plate of a lithium ion battery:
96 parts of lithium ion battery anode layered oxide LiNi 0.5Co0.2Mn0.3, 2 parts of binder PVDF and 2 parts of conductive carbon black are dispersed in N-methyl pyrrolidone to obtain uniform anode active material slurry, then the slurry is uniformly coated on two surfaces of an aluminum foil current collector, and the anode plate PL with the surface density of 380g/m 2 is obtained through drying and roller press compaction.
(2) Preparing a negative electrode sheet:
95 parts of graphite, 2 parts of styrene-butadiene rubber, 1.5 parts of sodium carboxymethylcellulose and 1.5 parts of conductive carbon black are mixed and dispersed in deionized water to obtain uniformly dispersed anode active material slurry. And coating the prepared slurry on one side of a copper foil, drying, compacting the pole piece by a roller press, and obtaining the negative pole piece NL with the surface density of 236g/m 2.
(3) And (3) assembling a battery cell:
Sequentially stacking the prepared positive electrode plate PL, diaphragm (composed of polyethylene base material 9 micron+2 micron ceramic coating) and negative electrode plate NL, so that the diaphragm is positioned between the positive electrode plate and the negative electrode plate, and stacking to obtain a bare cell; and placing the bare cell in an aluminum plastic film outer package.
(4) Preparation of electrolyte:
In a glove box filled with argon, the moisture content was < 0.1ppm and the oxygen content was < 0.1ppm. And (3) preparing a primary injection electrolyte: mixing Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) according to a mass ratio of 2:5:3 to obtain an organic solvent, slowly adding 17wt% of lithium hexafluorophosphate (LiPF 6) and 2wt% of lithium difluorosulfimide (LiFSI) based on the total weight of the primary injection electrolyte into the organic solvent to a mixture of the organic solvent and lithium salt, finally adding 2wt% of ethylene carbonate (VC) based on the total weight of the electrolyte, and uniformly stirring to obtain the primary injection electrolyte of the lithium ion battery. And (3) preparing a secondary injection electrolyte: mixing Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) according to a mass ratio of 2:5:3 to obtain an organic solvent, slowly adding titanium acetate (Ti (CH 3COO)3) accounting for 7wt% of the total weight of the secondary injection electrolyte into the organic solvent, and uniformly stirring to obtain the secondary injection electrolyte of the lithium ion battery.
(5) Liquid injection and pre-circulation
First liquid injection: the battery cell is dried in vacuum at 85 ℃, 105 g of the prepared primary injection electrolyte is injected into the dried battery cell after the water reaches the standard, and the battery cell is packaged, kept stand, hot-cold pressed and formed according to the common method in industry.
Pre-cycling: and placing the battery cell in a 45 ℃ incubator, and standing for 30 minutes to keep the lithium ion battery at a constant temperature. The lithium ion battery reaching the constant temperature is charged to 4.5V at a constant current of 1C, then charged at a constant voltage until the current drops to 0.05C, and then discharged to 2.8V at a constant current of 1C.
And (3) liquid injection for the second time: and injecting 45 g of the prepared secondary injection electrolyte, packaging, performing laser welding and sealing on the battery aluminum shell and the cover plate, aging the battery core, separating the capacity, testing the K value, packaging and the like, and thus completing the preparation of the lithium ion battery.
Examples 15 to 35 and comparative examples 4 to 6
Examples 15 to 35 and comparative examples 4 to 6 were prepared by the above lithium ion battery preparation method of example 14, and specific substances and contents are shown in table 2 below.
TABLE 2
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Test case
Performance test: the sodium ion battery and the lithium ion battery obtained in the above examples and comparative examples were subjected to related performance tests, and the specific test methods are as follows:
Sodium ion cycle performance test: and placing the sodium ion battery in a 45 ℃ incubator, and standing for 30 minutes to keep the sodium ion battery at a constant temperature. The sodium ion battery with constant temperature is charged to 4.0V at a constant current of 1C, then is charged at a constant voltage until the current is reduced to 0.05C, then is discharged to 1.5V at a constant current of 1C, and the cycle is repeated, the discharge capacity of the first circle and the discharge capacity of the last circle are recorded, and the capacity retention rate is calculated according to the following formula (three parallel samples are measured for each group, and the energy retention rate is the average value of three cells).
And (3) testing the cycle performance of lithium ions: and placing the lithium ion battery in a 45 ℃ incubator, and standing for 30 minutes to keep the lithium ion battery at a constant temperature. The lithium ion battery with constant temperature is charged to 4.5V at a constant current of 1C, then is charged at a constant voltage until the current is reduced to 0.05C, then is discharged to 2.8V at a constant current of 1C, and the cycle is repeated, the discharge capacity of the first circle and the discharge capacity of the last circle are recorded, and the capacity retention rate is calculated according to the following formula (three parallel samples are measured for each group, and the energy retention rate is the average value of three cells).
The n-th cycle capacity retention (%) = (n-th cycle discharge capacity/first cycle discharge capacity) ×100%.
And (3) cyclic gas production test: according to the above-mentioned cycle performance test method, the battery after 500 cycles is subjected to gas test. The liquid injection port is connected with the gas guide pipe, gas is led into the measuring cylinder with the back-off function (the measuring cylinder is filled with silicone oil), the gas volume is obtained by reading the silicone oil removal volume, (three parallel samples are measured in each group, and the gas volume is the average value of three electric cores).
K value test of self-discharge internal short circuit: the battery 1C was charged constant current to an upper limit voltage (lithium battery upper limit voltage 4.4V, sodium battery upper limit voltage 3.95V) at 25 ℃, then charged constant voltage to an up to current 0.05C at the upper limit voltage, left at 45 ℃ for 24 hours, then the voltage of the test battery was recorded as OCV1, left at rest for 24 hours, the test voltage was recorded as OCV2, k= (OCV 1-OCV 2)/2, three parallel samples were measured for each group, and the gas volume was averaged for three cells.
The specific test results are shown in the following table:
table 3 sodium ion battery test results
Table 4 lithium ion battery test results
From the above test results, the first injection in the embodiment of the invention is a conventional sodium ion or lithium ion battery electrolyte, and the formation and pre-circulation are performed to form a stable SEI film on the surface of the negative electrode. Then adding a secondary injection electrolyte containing a cationic additive, wherein the cationic additive can coat the uncoated surface of the positive electrode material in situ in the circulating process. Particularly, during the circulation process, the positive electrode particles are broken to expose new uncoated interfaces, and the cationic additive reacts on the surface of the positive electrode to form an in-situ coating layer. The in-situ coating layer can avoid the oxidation reaction of the new interface of the anode and the electrolyte in direct contact, thereby remarkably improving the problem of gas production of the battery in a circulating way. In addition, the cationic additive is added after formation and pre-circulation, so that stable SEI is formed on the surface of the anode, the cationic additive is not deposited on the surface of the anode in the circulation process, the problem of excessive self-discharge or internal short circuit is not caused, the K value is small (namely, the gas production and circulation are improved, and meanwhile, the self-discharge amplification and the internal short circuit are not caused), and the circulation capacity retention rate is improved.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims (4)

1. The electrolyte is characterized by comprising a primary injection electrolyte and a secondary injection electrolyte, wherein the primary injection electrolyte comprises alkali metal salt, a nonaqueous solvent and a primary additive; the alkali metal salt comprises lithium hexafluorophosphate or sodium hexafluorophosphate;
The secondary injection electrolyte comprises a cationic additive and a nonaqueous solvent, wherein the cation in the cationic additive is Ti 3+; the cation additive comprises at least one of nitrate radical, sulfate radical, sulfite radical, chloride ion, acetate radical, oxalate radical, hexafluoroarsenate radical, tetrafluoroborate radical, perchlorate radical, hexafluoroantimonate radical, difluorophosphate radical, 4, 5-dicyano-2-trifluoromethyl imidazole radical, bisoxalate borate radical, bismalonate borate radical, bisdifluoromalonate borate radical, malonate borate radical, difluoromalonate oxalate borate radical, trioxalate phosphate radical, tetrafluorooxalate phosphate radical, difluorodioxalate phosphate radical, difluorosulfonimide radical, bistrifluoromethanesulfonimide radical, fluorosulfonyl trifluoro methanesulfonimide radical and fluoride ion;
the cationic additive accounts for 5% -8% of the total mass of the secondary injection electrolyte;
the primary injection electrolyte accounts for 70% of the total mass of the electrolyte; the secondary injection electrolyte accounts for 30 percent.
2. The electrolyte according to claim 1, wherein the alkali metal salt is 12% -20% and the primary additive is 1% -5% based on the total mass of the electrolyte for one injection.
3. A secondary battery comprising the electrolyte according to any one of claims 1 to 2.
4. A powered device comprising the secondary battery of claim 3.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006107793A (en) * 2004-09-30 2006-04-20 Sony Corp Electrolyte and battery
CN106784589A (en) * 2016-12-08 2017-05-31 宁德时代新能源科技股份有限公司 Secondary battery and liquid injection method
WO2020145338A1 (en) * 2019-01-09 2020-07-16 日立化成株式会社 Electrolytic solution, electrolyte slurry composition, and secondary cell
CN116072969A (en) * 2023-03-08 2023-05-05 金阳(泉州)新能源科技有限公司 Electrolyte, preparation method thereof and lithium manganate battery
CN116845509A (en) * 2023-08-21 2023-10-03 蜂巢能源科技股份有限公司 Secondary liquid injection method and application thereof
WO2023216928A1 (en) * 2022-05-12 2023-11-16 珠海冠宇电池股份有限公司 Battery

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Publication number Priority date Publication date Assignee Title
JP2006107793A (en) * 2004-09-30 2006-04-20 Sony Corp Electrolyte and battery
CN106784589A (en) * 2016-12-08 2017-05-31 宁德时代新能源科技股份有限公司 Secondary battery and liquid injection method
WO2020145338A1 (en) * 2019-01-09 2020-07-16 日立化成株式会社 Electrolytic solution, electrolyte slurry composition, and secondary cell
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